Old English wascan "to wash, cleanse, bathe," transitive sense in late Old English, from Proto-Germanic *watskan "to wash" (source also of Old Norse vaska, Middle Dutch wasscen, Dutch wassen, German waschen), from PIE root *wed- (1) "water; wet." Related: Washed; washing.
Used mainly of clothes in Old English (the principal verb for washing the body, dishes, etc. being þwean). Old French gaschier "to stain, soil; soak, wash" (Modern French gâcher) is from Frankish *waskan, from the same Germanic source. Italian guazzare also is a Germanic loan-word. To wash (one's) hands of something is 1550s, from Pilate in Matthew xxvii.24. To wash up "clean utensils after a meal" is from 1751. Washed up "no longer effective" is 1923, theater slang, from notion of washing up at the end of a job.
tub n.
"open wooden vessel made of staves," late 14c., from Middle Low German, Middle Dutch, or Middle Flemish tubbe, of uncertain origin. Related to Old High German zubar "vessel with two handles, wine vessel," German Zuber. Considered to be unrelated to Latin tubus (see tube (n.)); one theory connects it to the root of two based on the number of handles. Also 17c. slang for "pulpit;" hence tub-thumper (1660s) "speaker or preacher who thumps the pulpit for emphasis."